Hard contact lenses have been available in many colors for over twenty years. Iris patterns have been placed inside both hard and soft contact lenses. Hard lenses are colored by adding the colorants to the monomer in the liquid state and polymerizing the colored monomer to form the colored hard lens material. Iris pattern lenses, both hard and soft, are made by laminating the painted or printed iris pattern inside the lens material. Spin casting is one of the most used methods of producing soft contact lenses. The lenses are produced in concave rotating molds so that colored lenses with a clear peripheral area have not been produced. If the colored area is allowed to extend to the edge it will be most visible and unattractive as the soft lenses are larger than the iris and extend over and cover part of the white part of the eye.
Lathe cut colored soft lenses are made from clear material in the xerogel state and later hydrated to produce soft lenses. The lenses are then dyed to provide lenses having a colored center and a clear periphery. U.S. Pat. No. 4,447,474.
In spin casting the two optical surfaces of the lens are formed simultaneously during polymerization. The outer lens surface is shaped by contact with the smooth mold surface, and the inner lens surface is shaped by the joint action of centrifugal forces, gravity and of surface tension on the polymerization mixture. Since the mold diameter is normally between 8 and 14 milimeters, the influence of surface tension of the ultimate lens shape is quite substantial.
One attempt employed a laminated structure with a painted opaque replica of the iris sandwiched between a clear and usually opaque plastic member. The result was a thick heavy lens which was difficult to fabricate and difficult to wear. A later attempt employed a colored opaque porous member surrounding a clear cylinder from which the lens was cut by lathing. This resulted in a lens having a pupil and iris pattern and the porous member had tendencies to flake and chip at the edge. (U.S. Pat. No. 3,454,332--Siegel). A third generation of colored lenses provided a thin layer of colored opaque markings placed in a clear material. The opaque colored marking radiated from the center of the clear material in a geometric pattern.
U.S. Pat. Nos. 4,472,327 and 4,460,523 disclose methods of making cosmetic hydrogel contact lenses which alter the apparent color of the iris by employing small light reflecting particles imbedded in a colored transparent matrix.
It is commonly known that any transparent conventional colored contact lens placed on a dark colored iris has little or no effect toward changing the apparent color of the eye.